Infrared detector module test system

ABSTRACT

A sensor test system is disclosed for testing the operation of infrared detector modules designed to be placed in earth orbit. The system includes an optical scene test generator (OSTG) for generating a scene representative of the earth&#39;s surface as seen from a satellite, and an object moving in relation to the earth&#39;s surface. Sensor chamber is disposed adjacent the OSTG for storing a detector module to be tested. Detector module is efficient within the sensor chamber to expose detector elements to the optical scene generated by the OSTG.

BACKGROUND OF THE INVENTION

The present invention relates to equipment for testing the operation ofsensor modules designed to conduct surveillance of the earth and thesurrounding atmosphere from a position in space.

Systems for monitoring activities on the earth and in the surroundingatmosphere have been constructed and deployed in space for many years.Some such systems are designed to map the surface of the earth, othersmonitor weather conditions and others monitor events relating tonational defense. While the accuracy and resolution of such systems hascontinually improved over the years certain applications require stillgreater resolution and real time use of the data. Though preciseinformation regarding the resolution of images returned from orbitingsatellites is not publicly available, it is generally known that LANDSAT(U.S.) and SPOT-G (Fr.) satellites provide resolution sufficient toidentify objects 15 meters long. More recently, the Soviet Union hasoffered to sell images from photographic satellites capable ofidentifying objects as short as 5 meters long. Because certainapplications require real time processing of the images of the observedscene, photographic techniques may be inadequate to satisfy therequirements of those applications. Certain applications require thatthe satellite imagery be done by means of infrared detector systemselectrically connected to processing circuitry. The need for highresolution, high speed processing and reliability in the extremes of thespace environment has required designers to press detector andprocessing technology to the existing limits and beyond. Consequently,the costs of constructing such satellite surveillance systems havebecome enormous as has the cost of launching such a system into orbit.In view of those costs and the uncertainty associated with such advancedtechnology it is highly desirable to vigorously test the surveillancesystem component in a space-like environment in order to reduce thepotential for failure in orbit.

The present invention is directed to a technique and system useful tosimulate the space environment in which detector modules are deployed,and to simulate the types of images which they are intended to detectand track. The invention is useful to generate various test scenariosand measures the detector module response to each scenario. The responseof the module to the various scenarios may then be evaluated todetermine the operability of the various detector module components. Thetest information may be used to replace inoperative detector modulecomponents, to facilitate the design of new modules and related supportelectronics, or to develop methods of processing and prioritizingdetection and communication functions associated with the module.

SUMMARY OF THE INVENTION

A sensor test system is disclosed for testing the operation of infrareddetector modules designed to be placed in earth orbit. The systemincludes an optical scene test generator (OSTG) for generating a scenerepresentative of the earth's surface as seen from a satellite, and anobject moving in relation to the earth's surface. Sensor chamber isdisposed adjacent the OSTG for storing a detector module to be tested.Detector module is efficient within the sensor chamber to exposedetector elements to the optical scene generated by the OSTG.

The system incorporates means for simulating a space environment withinthe OSTG by regulating vacuum temperature conditions therein.

The OSTG is operative to generate an infrared frequency image of theearth's surface, and an object moving in relation to the earth'ssurface. Various servo mechanisms are incorporated within the OSTG tosimulate various types of relative movement, such as missile trajectory,satellite drift, and satellite jitter. The intensity and spectralcontent of the infrared images may also be selectively varied tosimulate a variety of different testing conditions, each representativeof different operating scenarios.

In the presently preferred embodiment separately generated opticalimages, representative of a moving target and a background scene, arecombined at an optical image combiner and optically directed towardsinfrared detector elements disposed on the module to be tested. Thecombined image may thereafter be selectively toggled between differentlocations from the surface of the detector module. Such toggling iseffective to permit selective interrogation of different infrareddetector elements formed on the surface of the detector module.

A processing technique is also disclosed for figuring a set ofinstructions to perform desired processing functions, such as thosefunctions useful to regulate the operation of the sensor test system.However, it is to be understood that the processing technique hasapplication beyond the operation of the sensor test system disclosedherein.

The process is self configuring and permits real time processing of databy variably configuring libraries of general function modules. Inaccordance with the process a library of general function modules areprovided in predetermined priority levels. Those modules are selectivelylinked only as necessary to implement the desired processing functions.This data is provided to the linked functional modules to facilitateimplementation of the desired processing functions by the linkedmodules. Outputs are then communicated from the linked functionalmodules only to selected data presentation devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary satellite generallyillustrating its various components;

FIG. 2 is a perspective view of an exemplary detector focal planeincorporated in the satellite illustrated at FIG. 1, with portionsenlarged;

FIG. 3 is a block diagram illustrating the basic configuration of asensor test system for testing detector modules such as thoseillustrated at FIG. 2;

FIG. 4 is a top view of the sensor chamber and the OSTG illustrating theprincipal mechanical components thereof.

FIG. 4a is a perspective view of optical filters 94, 96, shown generallyat FIG. 4.

FIG. 5 is a perspective view of the construction of the OSTG illustratedat FIG. 4;

FIG. 6 is a further perspective view of the OSTG illustrated at FIG. 4;

FIG. 7 is a functional block diagram of the control circuitry to operatethe toggle servo 117;

FIG. 8 is a block diagram illustrating the priority levels establishedby the programming within the controller 49.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

The detailed description set forth below is intended merely as adescription of the presently preferred embodiment of the invention, andis not intended to represent the only form in which the presentinvention may be constructed or utilized. The description below setsforth the functions in sequence of signals that are affected by theinvention in connection with the illustrated embodiment. It is to beunderstood, however, that the same, or equivalent functions where signalsequences may be accomplished by different embodiments that are alsointended to be encompassed within the spirit and scope of the invention.

FIG. 1 of the drawings generally illustrates an infrared detector systempayload disposed within an orbiting satellite system. The satellitesystem generally incorporates an optical system which focuses objectswithin the field of view on the surface of a detector focal plane. Thefocal plane is formed of electro optical components adapted to detectobjects within the field of view and to generate electrical signalsresponsive to images of those objects. By analyzing the pattern ofinformation produced by the individual detector elements and correlatingthat information over time in various ways a detailed image of the areawithin the field of view can be generated. The precise satellitestructure, the structure of the detector modules used to form thedetector focal plane, and the precise manner in which the informationfrom the detector elements is processed is not intended to be alimitation with respect to the present invention, which, in its broaderaspects, has application to all types of satellite and detector systems.Thus, the reference to particular types of detector modules andelectronic systems compatible with those detector modules is intended asexemplary of one manner in which the present invention may be utilized.Reference is made to the following patents which are representative ofthe present state of the art in relation to the construction of infrareddetection systems and related support electronics having application tospace surveillance systems.

U.S. Pat. No. 3,582,714 CARSON ET AL.

U.S. Pat. No. 3,970,990 CARSON ET AL.

U.S. Pat. No. 4,283,755 TRACY

U.S. Pat. No. 4,304,624 CARSON ET AL.

U.S. Pat. No. 4,352,715 CARSON ET AL.

U.S. Pat. No. 4,354,107 CARSON ET AL.

U.S. Pat. No. 4,103,238 CLARK

U.S. Pat. No. 4,525,921 CARSON ET AL.

U.S. Pat. No. 4,551,629 CARSON ET AL.

U.S. Pat. No. 4,592,029 ALTMAN ET AL.

U.S. Pat. No. 4,618,763 SCHMITZ

U.S. Pat. No. 4,646,128 CARSON ET AL.

U.S. Pat. No. 4,659,931 SCHMITZ

U.S. Pat. No. 4,675,532 CARSON

U.S. Pat. No. 4,672,937 CARSON ET AL.

The teachings of the above cited references are incorporated herein byreference.

FIG. 1 generally illustrates a satellite 11 shown in Earth orbit. Theportions of satellite 11 of particular interest include an opticalsystem 13, detector focal plane 15 and data processor 17. The optics 13function to image objects within the satellite field of view on thesurface of focal plane 15. Optics 13 may include scanning mechanismsand/or staring mechanisms, depending on the particular function of thesatellite 11. The optics 13 may include various enhancements, such asmeans for reducing the effects of radiation from the sun, means forfiltering the light frequencies passing through the optical system, andmeans for toggling the location of the image on the surface of focalplane 15 in order to derive certain information from the image.

As described in more detail below, the focal plane 15 may be any of avariety of constructions, utilizing a variety of different materialssuitable to operate in a space environment. The focal plane 15 functionsto derive electrical signals from the image focused by optical system 13and to communicate such electrical signals to the data processor 17.Processor 17 directs interrogation of the focal plane 15 and iscontrolled by signals from ground operations 19.

Referring to FIG. 2 an exemplary focal plane useful in the applicationillustrated at FIG. 1 is shown in more detail. As shown at FIG. 2 thefocal plane 20 is defined by a housing 21 which holds a substantialnumber of individual subarrays 23 disposed to have edge portions thatcollectively form the front face of detector focal plane 20. Eachsubarray 23 is comprised of a plurality of modules 25, with each moduleis comprised of a plurality of separate layers 27. Integrated circuits29 may be mounted on the layers 27 to facilitate on-focal-planeprocessing of data and interrogation of detector elements. Detectorarrays 31, each containing a plurality of detector elements are formedalong a vertical edge surface of the modules and are in electricalcommunication with the integrated circuits via conductive paths formedon the surface of the layers 27. A buffer board 33 may be disposedintermediate the front face of module 35 and the detector arrays 31 tofacilitate interconnection and to isolate the detector arrays frommechanical stress generated by expansion or contraction of the module25. Further details describing the construction of such exemplarymodules are set forth in the above cited U.S. Patents. Exemplaryintegrated circuits suitable for incorporation with the modules includecircuits disclosed in the following mask work registrations, thesubstance of which is incorporated herein by reference:

MW 3147 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR DETECTOR CIRCUIT INCLUDINGGAIN NORMALIZATION AND ANALOG TO DIGITAL CONVERTER

MW 3145 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR MULTIPLEXER

MW 3148 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR LINEAR AMPLIFIER

MW 3146 CUSTOM INTEGRATED CIRCUIT LAYOUT INCLUDING CHOPPER STABILIZEDAMPLIFIER

MW 3150 CUSTOM INTEGRATED CIRCUIT SCANNING CIRCUIT

MW 3144 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR DETECTOR CIRCUIT INCLUDINGMODIFIED BANDPATHS AND GAIN CHARACTERISTICS

MW 3151 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR SIGNAL PROCESSOR

MW 3149 CUSTOM INTEGRATED CIRCUIT LAYOUT FOR STARING CIRCUIT

FIG. 3 illustrates the basic block diagram of the system for testing theoperation of the modules 25. The principal elements of the system 40include the sensor chamber 41, adapted to hold a module 25 to be tested,the optical scene test generator 43 (OSTG), adapted to generate theoptical image for display to the module, and the support electronics 45adapted to operate and gather data from the subarray 23 or module 25. AVAX 11/785 computer 47 regulates the operation of the supportelectronics. The computer 47 operates under the direction of controlprograms and in accordance with instructions entered into controller 49,which may be a personal computer such as an IBM (TM) personal computer.Detailed programming information for an exemplary program to enable thefunctions of controller 49 are disclosed in an unpublished appendixsubmitted herewith.

Pursuant to the instructions resident in controller 49 the VAX computer47 functions to regulate operations in the OSTG 43 and sensor chamber41, as well as to establish the state of support electronics 45 andestablish communications paths to output and store test information fromthe sensor chamber 41. As described more fully below the sensor chamber41 and OSTG 43 include servo mechanisms adapted to regulate the positionof elements therein. The sensor chamber 41 includes servo mechanisms toorient a detector module to simulate the various angles at which themodule may be disposed in relation to the Earth's surface. The OSTG 43includes several servos to simulate, for example, movement of the Earthscene, movement of a target in motion in relation to the Earth scene,drift and jitter, representative of relative movement between thesatellite and Earth scene and toggling of the imagery across the moduledetector array surface. Depending upon the particular test scenariodefined by controller 49, the VAX computer 47 orients the various servomechanisms and regulates the vacuum pumps and infrared sources toprovide scenes and orientations representative of the desired testenvironment.

Referring again to FIG. 3, it is to be understood that the particularorientation of visual displays and recording and analyzing devices isintended to be exemplary of but one embodiment of the invention and isnot intended to be limiting of other embodiments wherein the same orsimilar regulation or recording functions are implemented in a differentmanner. In the illustrated embodiment, data management is accomplishedby the DR11W connector between the VAX computer 47 and supportelectronics 45. IEEE 488 connectors communicate formatted data from theVAX computer 47 to plotter 55. Information stored on the real time diskis available for display on VICOM 53 under the control of VAX 47.Plotter 55 provides another means for graphically illustrating the datacommunicated to VAX 47. Another IEEE 488 connector is used tocommunicate signals between the VAX computer 47 and power supply 57.Oscilloscope 59 and digital volt meter 61 are used to monitor thesignals communicated along this conductor as well.

The graphics engine 63, implemented as a TEK 4126, provides real timedisplay of high resolution images of test conditions. Graphics engine 63operates in conjunction with controller 65, which may be implemented asa TEK 4132 or 4301. Microvax 67 is also connected to the ethernet andserves to provide processing of the test conditions and illustrating theenvironmental data such as vacuum, temperature or servo position data.

Pursuant to the program architecture and instruction list described morefully below, VAX computer 47 also communicates with controller 49 via anRS232 conductor, shown to include lines TTAO . . . TTD7. In the presentembodiment not all lines of the RS232 connectors are utilized and itshould be understood that different display requirements or systemcomponents may necessitate the communication of different signals orsignal formats along portions of the RS232 connector. However, in thepresently preferred embodiment lines TTAO-TTA3 are directed to a displayterminal to display information regarding vacuum, vacuum pressure,temperature and other environmental conditions within the sensor chamber41 or OSTG 43. Line TTA4 is directed to an external printer to print outerror messages as may be generated by the VAX computer 47. LinesTTBO-TTB3 communicate signals to a low or medium resolution graphicdisplay device to facilitate real time functions such as illustration ofhistograms representative of the test data. Line TTB5 communicatessignals between the VAX computer 47 and a test operator's console. Inthe presently preferred embodiment the test operator's console, i.e.controller 50, is implemented as a Macintosh™ computer manufactured byApple Computers, Inc. The console functions to make the system "userfriendly" by translating operator instructions to a data formatcompatible with the VAX computer 47, thereby avoiding the need fordirect input of signals to the VAX computer 47 in a format that may bemore complicated for the operator. The "C" lines, e.g. TTCO/TTC4 may beused to provide communication between VAX 47 and remote controllers,such as other IBM™ personal computers located in a test lab. The "C"lines may also be used to facilitate expansion, calibration inside thechambers, temperature regulation, etc.

It should be understood that various control circuits can be used toregulate the operation of the sensor chamber and OSTG and to display andstore the test conditions and responsive data. Accordingly, the abovedescription is intended to be exemplary and not limiting with respect toother control circuits that may be utilized to implement the functionsof the present invention. A further description of the construction ofsensor chamber 41 and OSTG 43 is provided below.

The OSTG 43 is designed to facilitate the presentation of different testscenarios to the detector module. As described in more detail below theOSTG includes means for generating infrared images representative of thesurface of the earth and of one or more objects moving in relation tothe surface of the earth. As is well known in the art such infraredimages can be presented using a variety of different means. The presentinvention uses a transmissive scene similar to a halftone image whichregulates the amount of infrared radiation passed through from an IRsource per unit area by the size and arrangement of opaque spots on thescene plate. The scene plate and target plate may be formed from acircular dish of silicon.

Imagery of one or more objects moving along the earth's surface, or inthe atmosphere or space adjacent the earth, is also achieved byradiating the template with an infrared light source. By varying theposition of the template the system can simulate movement of an objectunder investigation with respect to the earth. The intensity and shapeof the light may be varied to simulate different types of vehicles, e.g.solid or liquid fueled missiles. The size of aperture formed in thetemplate may also be varied in size and shape to represent objects ofdifferent sizes and shapes under investigation, e.g. planes, missiles,ships, etc.

By independently regulating the infrared source, movement of the targettemplate and the relative position of servos 79, 101, 107, 117, 123(FIG. 4) the system can simulate relative movement between the earth,the satellite, and the object under investigation. Different types ofrelative position or movements can be simulated in multiple ways. Forexample, movement of the earth with respect to the detector module maybe simulated by either moving the background template 99 or the detectormodule 25. Other types of relative movement may similarly be affected indifferent ways as will be apparent to those having ordinary skill in theart in view of the present disclosure. Different templates and aperturesmay be used to produce different test scenarios which are then regulatedby program control.

Referring to FIG. 4, a top view of the construction of the sensorchamber 41 and OSTG 43 is provided. Sensor chamber 41 is a thermalvacuum chamber comprising housing 75 which is evacuated by means ofvacuum pump 77. In practice the vacuum pump 77 may be a high speedvacuum control pump such as that sold by CTI-Cryogenics, model CT-10,and is operative to draw vacuum to a level of 1 time 10⁻⁶ atmos attemperatures between 88°-145° K. Chambers 43, 41 may be cooled to spacetemperatures using liquid nitrogen from an external source. In thepresently preferred embodiment internal heaters are connected to thedewars to stabilize each dewar at the test operating temperature.Detector module 25 is mounted within the sensor chamber 41 so as to bemovable in three axes, x, y and z, pursuant to actuation of detectormotion servos, collectively represented by servo 79. The servo 79 isoperative to position the detector module so as to image the test sceneon the surface of the detector arrays 31 and to orient the detectormodule 25 at a desired angle of inclination with respect to the testscene, simulating an angle of inclination of the satellite with respectto the Earth's surface. Servo 79 is connected to the VAX computer 47 viathe controller 66 and γVAX 67. (See FIG. 3) Detector module 25 is inelectrical communication with support electronics 45 to facilitateselective interrogation of detector elements within detector arrays 31and to communicate detector element outputs in response to suchinterrogation. In the presently preferred embodiment both sensor chamber41 and OSTG 43 are mounted on a granite testbed that is isolated fromthe ground by hydraulic suspension means. This permits the sensorchamber 41 and OSTG 43 to be isolated from vibrations in the ground orsurrounding building which would introduce distortion to the testresults. As previously described certain initial processing of thedetector signals may be accomplished within integrated circuits 29 (seeFIG. 2) disposed directly on the module's surface. More complexprocessing of the output of detector module 25 is affected by the VAXcomputer 47 which also correlates the module output signal with testscenario data. A listing of instructions resident in the VAX computer 47is submitted herewith. Other functions, such as bias regulation, clocksignals, sampling and multiplexing of data may be affected by thesupport electronics 45.

FIG. 4 further shows a top view of the layout of the OSTG 43. OSTG 43includes housing 85 disposed adjacent sensor chamber housing 75. Housing85 is evacuated by vacuum pumps 87 which may be constructed similar tovacuum pumps 77 that evacuate the sensor chamber 41. In the preferredembodiment two infrared light frequency sources 89 and 91 are disposedexterior to the OSTG 43 and directed to transmit infrared light towardsoptical systems disposed within housing 85. IR sources 89 and 91 mayalternatively be disposed within housing 85 as may be permitted by theavailable space within housing 85. One advantage of disposing the IRsources outside of housing 85 is that optical filters, such as opticalfilter 93, may be replaced without the need to bring the OSTG to normalatmosphere conditions. Filters, such as filter 93, may be useful to varythe intensity or to filter a portion of the IR frequency spectrum totest the detector module responsiveness to selected frequencies withinthe IR frequency range. As is well known to those of ordinary skill inthe art certain frequencies ranges within the IR range are indicative ofdifferent objects or backgrounds. For example, certain portions of theIR frequency range are more representative of a solid rocket boosterburn whereas other portions of the IR frequency range may berepresentative of a liquid rocket booster burn. By selectively filteringthe light entering the OSTG the detector module may therefore beselectively tested for detection of certain types of vehicles.

In the preferred embodiment IR source 89 is intended to be useful togenerate a scene representative of the Earth and other backgroundconditions, e.g. objects on the earth's surface or cloud cover, whereasthe IR source 91 is useful to generate an image representative of anobject moving in relation to the background. The IR sources 89 and 91may be implemented using an infrared light source, such as the modelWS161-55, sold by Electro-Optical Industries.

The IR frequency light from IR source 89 enters housing 85 throughwindow 95. IR source 89 is set to the desired spectral temperature. IRsource 91 is also set to the desired spectral temperature. Filters 93,97 may be implemented as gradient filters which may be rotated to adesired density filter to regulate light from IR source 91 enteringhousing 85. It is anticipated that spectral filters may also be usedselectively filter the spectral content of the IR light entering the OST643. A combination of spectral and neutral density filters are utilizedin the sensor test chamber 41, as described in connection with FIG. 4A.Referring to FIG. 4, light from IR source 89 passes through filter 97and impacts on background template 99, preferably formed of sapphire.Background template 99 may be changed in order to conduct test scenarioswherein different portions of the earth's surface are intended to serveas background for the test. Background template 99 is typically providedwith a series of small apertures which, upon the passage of IR lightfrom IR source 89, generates an infrared signature similar to thatobserved from satellites looking at particular portions of the Earth'ssurface. Background template 99 may be changed in order to conduct testscenarios wherein different portions of the Earth's surface are intendedto serve as background for the test. Background servo 101 facilitatesmovement of the background template 99 to facilitate simulation ofmovement of the background in relation to the detector module 25 and/orthe target.

As previously noted IR source 91 is useful to generate an infraredsignal used to simulate a target. The IR frequency signal passes throughoptical filter 93. The signal from filter 93 passes into housing 85through window 103 and impacts target template or membrane 105,preferably formed of sapphire. Target template 105 is provided with oneor more apertures of selected sizes intended to produce thecharacteristic infrared signature of one or more particular types ofvehicles or other objects. By varying the intensity of the signal fromIR source 91, and the size of the aperture within target template 105,various types of vehicles or other objects can be simulated. Targetservo 107 functions to move the target template 105 to simulate movementof the target in relation to the background and/or the detector module.As with background servo 101, target servo 107 may in practice be formedof a plurality of servos adopted to facilitate three-axis movement oftarget template 105. By selective actuation of target servo 107 varioustypes of trajectories and speeds can be simulated such that thecharacteristic flight paths of different types of vehicles can besimulated. For example, cruise missiles or submarine launched ballisticmissiles may travel trajectories that are different than thetrajectories of ground based intercontinental ballistic missiles. Inorder to test the responsiveness of the detector module throughdifferent types of vehicles the target template may be changed and/orthe action of target servo 107 can be varied in accordance with the testprogram implemented in controller 49 (see FIG. 3).

It should be understood that more than one template may be used toimplement the functions of target template 105. In the embodimentillustrated at FIG. 4 a single target template is utilized and,therefore, each target image produced by the template would move in acommon manner. However, if more than one target template was used it ispossible to simulate a plurality of targets moving relative to eachother. It is also anticipated that in alternate embodiments a dynamic IRscene and multiple IR targets may be imaged directly off a cathode raytube onto the focal plane.

The images generated by the IR light passing through background template99 and target template 105 are directed to optical image combiningdevice (beam splitter) 109. Device 109 functions to receive both opticalimages and to direct them in such a manner that they ultimately pass outof housing 85 through window 111, into housing 75 through window 113,filters 94, 96 and impact on the detector arrays 31 disposed on thefront surface of detector module 25. In the presently preferredembodiment device 109 communicates the images from templates 99 and 105to toggle mirror 115 whereupon the images are reflected to detectormodule 25.

FIG. 4a illustrates in more detail the construction of filter wheels 94,96, disposed within the sensor test chamber 41. Filter wheel 94 may beimplemented as a neutral density wheel, rotatable to present differentdensity gradient filters. Filter 96 may be implemented as a spectralwheel, rotatable to present different spectral density filters. Byrotating the spectral filter wheel 96 the infrared frequency of thelight signal presented to the detector module 25 may be selectivelyvaried. As will be apparent to one of ordinary skill in the art theselective rotation of filter wheels 94 and 96 will enable the testing ofthe detector module 25 under a variety of different conditions.

Toggle mirror 115 is an optional element in the sensor test system whichis utilized dependent upon the construction of detector module 25. Insome constructions detector module 25 may be formed such that adjacentlines of detector elements forming the detector arrays 31 areconstructed or connected to be responsive to different portions of theIR frequency spectrum. Thus, by toggling the image such that the sameimage portion is moved from one line of detectors to the adjacent lineof detector elements (or to any other line of detector elements)information particular to a portion of the IR frequency spectrum may beextracted from the test image without the need for increasing populationof detector elements within the detector array.

As described in more detail in connection with FIG. 5, image combiningdevice 109 includes lens 119 which is connected to jitter servo 121which will selectively move the lens 119 in a manner to representsatellite jitter. The jitter servo 121 moves the target in backgroundwith respect to the detector module in such a manner to simulatevibration of the satellite. Drift servo 123 is connected to turntable125 which also supports the lens 119. Drift servo 123 moves the mirrorsupport 125 in such a fashion as to provide slow rate movement of thetarget and background in a manner to simulate drift of the satellite asit orbits the Earth. As will be clear to those of ordinary skill in theart the relative operation of the various servos 101, 107, 117, 121 and123 is performed under program control in response to the particulartest scenario implemented by controller 49.

FIG. 5 is a perspective view of the OSTG illustrated at FIG. 4. Theconstruction shown at FIG. 5 generally illustrates the opticalarrangement implemented within the OSTG for combining the scene andtarget images, and for permitting relative movement therebetween. Thetarget path is initiated with IR source 91 and passes through filter 93,condenser lens assembly 92, target mask 105, target collimator 94, andlens 119 of the beam splitter 109.

The scene path commences with IR source 89 and passes through filter 97,scene condenser lens assembly 96, scene template 99, scene collimator98, and then impacts lens 119 of beam splitter 109.

The beam splitter 109 functions to combine the reflected scene imagesand transmitted target image on the surface of toggle mirror 115. Thecombined image is then communicated to the detector module through exitlens assembly 100.

FIG. 6 generally repeats the optical structure shown at FIG. 5 with thefurther inclusion of the mechanical supports and servos which regulatemovement of the target and scene images. FIG. 6 illustrates the targetservo 107 used to control movement of the scene mask 105. Backgroundservo 101 operates to regulate the movement of the background mask 99.Both the background and target servos permit regulation of highresolution movement in the X, Y and Z planes. Toggle servo 117 regulatesthe movement of toggle mirror 115 as more fully set forth in connectionwith FIG. 7.

As will be recognized by one of ordinary skill in the art the particularoptical assembly utilized to generate and vary the position of thetarget and scene images may be varied in accordance with the particulardesign requirements and test scenario to be implemented. Accordingly,the particular function set forth in connection with FIGS. 5 and 6 isintended to be only exemplary of the presently preferred embodiment ofthe invention.

FIG. 7 is a functional block diagram illustrating the electrical controlcircuitry to operate mirror toggle servo 117. The circuit set forth atFIG. 7 generally demonstrates the manner in which servo 117 is operatedto regulate the motion of toggle mirror 115.

The toggle mirror assembly 115 is moved between two positions inresponse to the motion of toggle mirror servo 117. Upon receipt ofsignals from level shifter 207 the toggle mirror servo 117 moves thetoggle mirror in alternate directions. Unit sensors 213, 215 act toterminate any further movement by the toggle mirror servo 117 beyonddesignated limits. Power to level shifter 207 is provided by powersupply 205. The level shifter 207 enables pulse generators 209, 211which in turn generate a one-bit position signals that motivate togglemirror servo 117 to move in the desired direction.

FIG. 8 is a block diagram listing the priorities of operation of thesoftware resident in the VAX 11/785 computer to operate the function ofthe sensor test system. As shown at FIG. 8, the level 1 program modulerefers to the laboratory test operating system (LTOS), i.e. the rootprogram or test system which operates to specify the type of tests andterminals to be used in the particular test scenario to be run.Functionally, the LTOS program interactively defines a test requirement,loads all required tasks, allocates all shared buffers, links allrequired lower level functional modules, monitors the status of alltasks and waits for operator input after successful completion of alltasks. Further details of the LTOS and other level systems are set forthbelow, with a detailed instruction list being attached hereto as anunpublished appendix.

Priority level 2 is assigned for the task of data acquisition and datareplay. The level 2 module receive requirements from the LTOS programand shares buffers with other level modules. The module loads raw datafrom the support electronics into associated buffers and, in response toLTOS signals the module transfers the information contained in thecurrent buffer onto a storage disk during acquisition and sets a doneflag for the LTOS after the acquisition is complete. The module checksfor operation of level 3 tasks and triggers the operation of level 3tasks.

The level 2 program module includes an acquisition (Acq) module whichacquires data from the support electronics 45 and controls level 3procedures via event flags. If level 3 procedures fall behind the datamodule stores the raw data during acquisition. The level 2 module alsoincludes a replay module which replays data from a previously loadeddisk data file. The replay module is activated either from the LTOS(playback) or acquisition module where the real time processing does notkeep abreast of the data input. The replay module also controls level 3processors via event flags.

The level 2 replay module is also loaded by the LTOS to receive testrequirements and operating speed information. The module is triggered bythe LTOS module to start playback of a previous test. The replay moduleloads frames of data onto buffers and triggers level 3 tasks. Uponcompletion of the replay module tasks the module also sets a done flagfor the LTOS to indicate that the replay function is complete.

The level 3 tasks include all real time processing tasks. The level 3module processes the data received from the support electronics toeffect such processes as the construction of a histogram, XY plotting,mapping, sum square, difference, threshold, M of N filtering, etc. Level3 modules are loaded by the LTOS from which they also receive the testrequirements. The LTOS allocates buffers to the level 3 module, some ofwhich may be shared with level 2, 4 or 5 modules. The processing modulesoperate on input data and set flags for the level 2 modules whenprocessing is complete. The flags then trigger the next higher leveltask.

The level 4 modules operate to format the data for output. The modulesperform an averaging and other functions on the data stored in the databuffer, and collect statistics for output on assigned output devices.The functions include RMS, Averaging, Comparing, PSD (Power SpectralDensity, D* (figure of merrit), Normalize and Trac. As with the othermodules the level 4 module shares buffers with other level modules. Whenthe level 4 tasks are complete the module triggers the flag permittingthe next higher level tasks to proceed.

Level 5 module functions to regulate output service tasks, such as theoutput of data generated by the level 4 modules. As with the othermodules, level 5 modules are loaded by the LTOS with the testrequirements and the configuration of assigned output devices. Buffersare allocated by the LTOS which may be common with other level modules.The level 5 modules may be triggered by the level 3 or level 4 modulesto process the assigned data. When processing is complete the level 5module becomes inactive. The level 5 functions include static plot,spatial mapping, three dimensional mapping, XY output, spatialfiltering, and histograms.

The last level module is the level 6 module which performs commonhardcopy output tasks, such as hardcopy histogram plot, hardcopy XY plotand hardcopy list. Again this module is loaded by the LTOS with testrequirements and buffer allocations. The module typically shares onebuffer with each specified task on levels 3, 4 or 5 that request thehardcopy. The module reads hardcopy parameters from the system mailboxand generates the required number of hardcopies.

It is to be understood that the advantage derived by the multi-levelprogram structure implemented in the VAX 47 is that it permits thevarious tasks to be identified for a particular test, allowing dynamicconfiguration of the program to meet the requirements associated with aparticular test scenario. The particular program portions are modular inimplementation and may be incorporated into the processing based uponeither a preset test sequence or a recognition of the need for suchprogram portion based on an analysis of output data from the module. Forexample, jitter and clutter rejection, appropriate temporal and spatialfiltering and other rejection criteria to discard false data may beimplemented as a consequence of data from the module indicating thatnoise vibrations, momentary or periodic scene vibrations or focal planefaults are present.

The LTOS module directs configuration of the lower level modules suchthat only those portions of the level 2 to 6 modules that are needed fora particular test scenario are utilized. The remaining portions becometransparent to the programming and do not delay processing by theportions being utilized. This advantage is particularly useful when itis desired to process large amounts of data on a real time basis.

The multi-level program thus operates to link select general functionmodules in accordance with a desired processing functions. In such amanner only the general function modules that are essential to thedesired processing function need be linked. The remaining processingmodules form no portion of the instruction set and do not delay theoverall operation of the program. The program becomes self-configurableupon defining the sources of data, the processing functions to be formedon that data, the priority sequence of the various processing functionsand the desired manner of storing and presenting the process data. Theroot LTOS program operates to link the general function modules toreceive the collected data, process the data, store the data, anddisplay data as designated by relatively simple operation inputinstructions. An operator may simply indicate the source from which datais to be acquired, the analyzing or processing functions to be performedon the data and the console or other location at which the processedand/or raw data is to be presented or stored, and the LTOS orients thegeneric function modules to be configured in an efficient manner toimplement the operators instructions. Modules run only if there is datafor them to run. Modules that, for example, perform unneeded processingfunctions or communicate process data to non-designated displays orstorage devices are excluded from the linking arrangement and the systemneed not provide sufficient processing time to affect the functions ofunlinked modules. All programs on the same level run concurrently. Alsothe same module may concurrently run multiple programs, each with thesame or different parameters. The system is presently configured tooperate on 32,000 bits of data at a rate of 327,680 bytes per second.The system provides sufficient parallel processing capacity in order topermit concurrent operation. In the presently preferred embodiment eachlevel can run 31 concurrent programs. END INSERT D] Accordingly, theprogram operates to reduce processing time and thereby facilitate realtime processing of large amounts of data.

Where the large amounts of data make the data collecting and dataprocessing functions consume the real time capacity of the program, thedifferent priority levels permit functions such as data display to bedeferred in preference to high speed data storage devices which make thedata available for display at a later time.

It is to be understood that the particular operations that are performedon the data e.g. the particular operations performed by the generalfunction modules, may be varied without departing from the basicprinciples of the test configuration program. Thus, for example, thelevel 3 or level 4 modules may implement a variety of differentprocessing functions other than those described above.

A listing of the program information stored in controller 47 is appendedto this application as an unpublished appendix A. A brief review of theoperational characteristics of the program stored in controller 49 isset forth below to facilitate an understanding of the operation of theprogram to implement the functions of the laboratory test system. It isto be understood, however, that the specific program listings inappendix A and the descriptive information set forth below are providedby means of example only, and are not intended to represent the only wayin which the laboratory test system may be implemented, or that thenovel features on the program may be affected.

A general description of the interconnection of the various prioritylevels of general purpose modules, and the event flags used tofacilitate communication between the various levels is as follows:

    ______________________________________                                        EVENT FLAGS                                                                   ______________________________________                                        Level 1                                                                       SEND    LTOS Cluster 2 (16 Triggers from level 1 to                                   level 2 )                                                             RECEIVE LTOS Cluster 3 (1 common message from all levels                              except 6 )                                                            LEVEL 2                                                                       SEND    LTOS Cluster 3 (1 common message to level 1)                                  ACQ Cluster 2 (Buffer # [Bits 0 + 2], 1 real time                             trigger [Bit 3],                                                              1 replay trigger [Bit 4], Frame Count [Bits                                   5-17]                                                                 RECEIVE LTOS Cluster 2 (16 Triggers from Level 1)                                     ACQ Cluster 3 (32 Ready from Level 3)                                 LEVEL 3                                                                       SEND    LTOS Cluster 3 (1 common message to Level 1)                                  Real Time Cluster 2 (32 Triggers to Level 4, if                               required)                                                                     Hard Copy Cluster 2 (16 Common Busy, 16 Common                                Triggers to Level 6 if required)                                              ACQ Cluster 3 (32 ready to Level 2)                                   RECEIVE ACQ Cluster 2 (Buffer # [Bits 0-2], 1 real time                               trigger [Bit 3],                                                              1 Replay trigger [Bit 4], Frame Count [ Bits 5-17]                            from Level 2)                                                         LEVEL 4                                                                       SEND    LTOS Cluster 3 (1 common message to Level 1)                                  Process Cluster 2 (32 triggers to Level 5 if required)                        Hard Copy Cluster (16 common busy, 16 common                                  triggers to Level 6 if required)                                      RECEIVE Real time Cluster 2 (32 triggers from Level 3)                        LEVEL 5                                                                       SEND    LTOS Cluster 3 (1 common message to level 1)                                  Hard Copy Cluster 2 (16 common busy, 16 common                                triggers to Level 6 if required)                                      RECEIVE Process Cluster 2 (32 triggers from Level 4)                          LEVEL 6                                                                       SEND    Hard Copy 3 (16 common trigger to levels 3, 4,                                or 5)                                                                 RECEIVE Hard Copy 2 (16 common busy, 16 common triggers                               from Levels 3, 4 or 5)                                                ______________________________________                                    

In the presently preferred embodiment the LTOS loads the followingparameters to the various modules:

    ______________________________________                                        Parent process MSX name   10 char                                             Event flag clutter to use 10 char                                             Global memory name        10 char                                             Array size                 1 integer                                          Frames in test             1 integer                                          Name label for output tasks                                                                             40 char                                             Data scaling factor        1 F.P.                                             Number of output processors required                                                                     1 char                                             Name of first output process                                                                            10 char                                             Name of mailbox for first process                                                                       10 char                                             Label 1 for first process 20 char                                             Label 2 for first process 20 char                                             Qualifier word for first process                                                                         1 integer                                          Name of second output process                                                                           10 char                                             Name of mailbox for second process                                                                      10 char                                             Label 1 for second process                                                                              20 char                                             Label 2 for second process                                                                              20 char                                             Qualifier for second process                                                                             1 integer                                          Name of third process . . . n qualifier for                                   last process.                                                                 ______________________________________                                    

The following pseudo services are affected by the LTOS in response to aparticular scenario selected:

1. create buffer (logical name, size) [size is in bytes]

2. get buffer (logical name) [returns a pointer to buffer or zero if notavail]

3. create cluster (logical name, cluster number) [cluster number iseither 2 or 3]

4. get cluster (logical name, cluster number)

5. set flag (cluster number, logical bit) [logical bit is 1-31]

6. release cluster (cluster name)

7. release buffer (logical name)

8. Clear flag (cluster number, logical bit)

9. Read cluster (cluster number)

10. Wait for (cluster number)

11. Wait for and (cluster number)

12. Wait for or (cluster number)

The description below illustrates the particular sequence in which thecertain particular modules are implemented in the presently preferredembodiment. The exact implementation is set forth in the appendedprogram listing.

The main driver for the operation of a system may be a simple personalcomputer which configures the VAX computer to implement the testscenario. As described above, in the presently preferred embodiment themain driver is implemented in a Macintosh Apple Computer. The principalroutines affected by the personal computer are described below.

Main Driver Program

1. Call routine to get order from VAX on GPIB and put it intoaccumulator.

2. See if order is to relay another order to the OSTG.

3. If it is, go to subroutine to relay VAX order.

4. See if order is to read data from an SOTG unit and store it intomemory.

5. If it is, go to subrountine to read OSTG unit.

6. See if order is to write stored data in memory out to the VAX

7. If it is, go to subroutine that dumps memory contents out to the VAX

8. If order was none of the above, it is an unrecognized command andshould be ignored in this case, start over from step 1.

Relay Order Routine

1. Call routine to get order type from VAX on GPIB and put it intoaccumulator.

2. See if order type is for a three-byte (P3 outdip) instruction.

3. If it is, jump to branch that handles the three-byte case. (A)

4. Since we otherwise have a one-byte (p7 outdip) instruction callroutine to get byte from VAX on GPIB and put it into a register

5. If order involves stepping a scene stepper ONLY jump to B below

6. If order involves resetting the all commands done flag, jump to Cbelow.

7. Otherwise, just present instruction byte to p7 outdip

8. Go back to 1. in main driver routine.

A.

1. Call routine to get low byte from VAX and put it into the lower halfof a register.

2. Call routine to get high byte from VAX and put it into the upper halfof a register.

3. Present low byte to P3 outdip.

4. Present order to P2 outdip.

5. Delay enough time for CMD not done yet flag to assert.

6. Now watch flag until it deasserts.

7. When it does, present high byte to P3 outdip.

8. Present a no CMD command to P2 outdip.

9. Delay if necessary for CMD not done yet flag to assert.

10. Now wait for flag to deassert.

11. Then present order again to P2 outdip.

12. Delay again for CMD not done yet flag assertion

13. Wait for flag deassertion.

14. Jump back to 1. in main driver routine.

B.

1. Invert the X and Y step trigger bits.

2. Present the byte to P7 outdip.

3. Let it dwell there for about 1/1OO second.

4. If the X step trigger bit is low, invert it.

5. If the Y step trigger bit is low, invert it.

6. Present the byte to P7 outdip again.

7. Jump back to 1. in main driver routine.

C.

1. Store bits 0-3 in a holding register.

2. Put all l's in bits 0-3 in scene byte.

3. Invert the reset CMD done* bit.

4. Present byte to P7 outdip.

5. Let it dwell there for a time period.

6. Invert the reset CMD done* bit again.

7. Present the byte to P7 outdip again.

8. Restore bits 0-3 of the byte to their original values.

9. Jump to B above.

Store OSTG Data

1. Reset all counters and pointers.

2. Call routine to reset CMD done flag.

3. Send a global no CMD command via P2 outdip.

4. Wait for the not done yet flag in P4 indip to assert.

5. Now wait for it to disassert.

6. Monitor frame sync through its I/0 port and wait for it to go low ifit is high.

7. Wait for frame sync to go from low to high.

8. Send a command to update position readout to card 1 (if first timethrough loop) via P2 outdip.

9. Wait for the card 1 CMD running flag in p4 indip to assert.

10. Now wait for it to disassert.

11. Read lowbyte of data from PO indip and put into a register.

12. Read highbyte of data from P1 indip and put into a register.

13. Increment memory pointer and place lowbyte into memory.

14. Increment memory pointer and place highbyte into memory.

15. Send a no CMD command to card 1 (if first time through loop).

16. Wait for the card 1 CMD running flag in p4 indip to assert.

17. Now wait for it to disassert.

18. Jump back to 8. and do loop 5 more times, each time with a differentcard ID (6 total).

19. Read byte of data from P6 indip and put it into a register.

20. Read byte of data from P5 indip and put it into a register.

21. Increment memory pointer and place first (P6 in dip) byte intomemory.

22. Increment memory pointer and place second (P5 indip) byte intomemory.

23. Increment memory pointer and put a byte of 2ERD5 into memory, dothis twice.

24. Increment frame pointer

25. Call routine to check for an interrupt order from the VAX throughthe IEEE 488 interface.

26. If there is an interrupt order (except resume), go to step 29 below.

27. If frame counter=8192 then jump back to main driver step 1.

28. Else jump back to step 2 above.

29. Is interrupt order to abort?

30. If so, jump to main driver step 1.

31. Is interrupt order to suspend?

32. If so, do nothing but continuously call routine to check for aninterrupt order from the VAX until it comes.

33. If order is to resume, go to step 27 above.

34. Else jump to step 29 above.

Dump OSTG Data

1. Reset all counters and pointers.

2. Read byte of data from memory into accumulator.

3. Call routine to send it to VAX via the IEEE-488 Interf.

4. Increment memory pointer..

5. Have 128K bytes been sent?

6. If not, jump back to 2 above and do loop again.

7. Else jump back to main driver step 1.

What is claimed is:
 1. A sensor testing system for testing the operationof detector modules designed to be placed in earth orbit, said detectormodules having a plurality of detector elements, the systemcomprising:an optical scene test generator (OSTG) for generating anoptical scene representative of the earth's surface as seen from asatellite in space and an object moving in relation to the earth'ssurface, said OSTG comprising: a first dynamically positionable infraredfrequency light signal source for generating a first infrared frequencylight signal representative of the earth's surface; a second dynamicallypositionable infrared frequency light signal source for generating asecond signal representative of a moving object; an optical imagecombiner for receiving and combining the first and second infraredfrequency light signals, and for directing the combined first and secondinfrared frequency light signals toward the detector elements; and apositioning apparatus connected to each of said first and secondinfrared frequency light signal sources for dynamically positioning eachof said first and second infrared frequency light signal sourcesrelative to one another and relative to said detector modules such thatthe independent motions of a target and background may be simulated; anda sensor chamber disposed adjacent the OSTG for storing a detectormodule to be tested, said detector module having a first surfacecomprised of a plurality of detector elements and being positionedwithin the sensor chamber to expose at least a portion of said detectorelements to the optical scene generated by the OSTG.
 2. The system asrecited in claim 1 further including means for evacuating the OSTG tosimulate space environment therein.
 3. The system as recited in claim 2further including means to evacuate the sensor chamber to simulate aspace environment therein.
 4. The system as recited in claim 1 furthercomprising means to regulate the temperature within the OSTG to simulatea space environment therein.
 5. The system as recited in claim 1 furthercomprising means to regulate the temperature within the sensor chamberto simulate a space environment therein.
 6. The system as recited inclaim 1 wherein the OSTG is operative to generate an infrared frequencyimage of the earth's surface.
 7. The system as recited in claim 1wherein the OSTG is operative to generate an infrared frequency image ofthe moving object.
 8. The system as recited in claim 1 wherein the OSTGis operative to generate an infrared frequency image of the earth andthe moving object.
 9. The system as recited in claim 1 wherein the OSTGis operative to generate an infrared frequency image representative ofrocket plumes moving in relation to the earth's surface.
 10. The systemas recited in claim 1 wherein the OSTG is operative to simulate relativemovement between the earth and the detector module.
 11. The system asrecited in claim 10 wherein the relative movement between the earth andthe detector module is representative of the orbital drift of asatellite about the earth.
 12. The system as recited in claim 1 whereinrelative movement between the earth and the object is representative ofthe flight path of a missile.
 13. The system as recited in claim 12wherein the OSTG is operative to simulate missiles moving at differenttrajectories in relation to the earth's surface.
 14. The system asrecited in claim 10 wherein the relative movement between the earth andthe detector module is representative of satellite jitter.
 15. Thesystem as recited in claim 1 wherein the OSTG is operative to vary theintensity of the image of the object.
 16. The system as recited in claim15 wherein the object intensity is representative of different types ofvehicle propulsion systems.
 17. The system as recited in claim 1 whereinthe OSTG is operative to vary the size of the image representative ofthe object.
 18. The system as recited in claim 1 wherein the OSTG isoperative to vary the shape of the image representative of the object.19. The system as recited in claim 1 wherein the OSTG is operative tosimulate transient cloud cover between the earth's surface and thedetector module.
 20. The system as recited in claim 1 wherein saidoptical image combiner comprises a moveable lens disposed along the pathof said first and second light signals, said lens being adapted todirect the combined first and second light signals towards the detectorelements.
 21. The system as recited in claim 1 wherein the imagecombiner is moveable to simulate relative movement between the detectormodule first surface and both the first and second light signals. 22.The system as recited in claim 21 wherein the image combiner is moveableto simulate satellite jitter.
 23. The system as recited in claim 21wherein the image combiner is moveable to simulate satellite drift. 24.The system as recited in claim 1 further comprising a moveable togglemirror disposed within the OSTG, the toggle mirror being operative todirect the combined first and second light signals to differentlocations upon the first surface of the detector module.
 25. The systemas recited in claim 24 wherein the toggle mirror is operable to affectmovement of the combined first and second light signals with respect todifferent detector elements formed on the detector module first surface.26. The system as recited in claim 25 wherein the toggle mirror isoperable to vary the location of the combined first and second lightsignals by a distance corresponding to the space between adjacentdetector elements.
 27. The system as recited in claim 1 wherein thesensor chamber comprises a third servo mechanism for moving the detectormodule with respect to the optical scene generated by the OSTG.
 28. Thesystem as recited in claim 27 wherein the third servo mechanism isoperative to simulate different angles of inclination of the detectormodule with respect to the earth's surface.
 29. The system as recited inclaim 24 wherein the sensor chamber comprises a third servo mechanismfor moving the detector module to different orientations with respect tothe scene generated by the OSTG.
 30. The system as recited in claim 1wherein:(a) said first infrared frequency light signal sourcecomprises:(i) a first source of IR frequency light; and (ii) a firstscannable template formed to generate a first infrared frequency lightsignal representative of the earth's surface upon application of IRlight to the first template; (b) said second infrared frequency lightsignal source comprises:(i) a second source of IR frequency light; and(ii) a second scannable template formed to generate a second infraredfrequency light signal representative of a moving object uponapplication of IR frequency light to the second template; and (c) saidpositioning apparatus comprises template positioning apparatus connectedto each of said first and second templates for positioning each of saidfirst and second templates relative to one another and relative to saiddetector modules such that the independent motions of a target andbackground may be simulated.
 31. The system as recited in claim 1 wheresaid first infrared frequency light signal source, said second infraredfrequency light signal source, and said positioning apparatus compriseat least one cathode ray tube.
 32. The system as recited in claim 1wherein said first dynamically positionable infrared frequency lightsignal source comprises:(a) a first source of infrared frequency light;and (b) a first laser scannable template formed to generate a firstinfrared frequency light signal upon application of IR light to thefirst template.
 33. The system as recited in claim 32 wherein the firsttemplate is removable to facilitate the use of templates havingdifferent patterns of apertures formed thereon.
 34. The system asrecited in claim 32 wherein the first template is constructed to have afirst pattern of aperture formed therein, said first pattern ofapertures being designed to produce an image representative of a portionof the earth's surface as viewed from space.
 35. The system as recitedin claim 32 wherein the first template is formed of a sapphiresubstrate.
 36. The system as recited in claim 32 wherein the OSTGfurther comprises a first optical filter disposed intermediate the firstlight source and the first template, said first optical filter beingoperative to limit light frequencies contained within the IR lightapplied to the first template.
 37. The system as recited in claim 32wherein said positioning apparatus further comprises a first servomechanism for regulating the position of the first template.
 38. Thesystem as recited in claim 37 wherein said first servo mechanism isoperable to regulate the location at which the IR light is applied tothe first template.
 39. The system as recited in claim 37 wherein saidfirst servo mechanism is operative to simulate relative movement betweenthe detector and the earth's surface.
 40. The system as recited in claim37 wherein said first servo mechanism is operative to simulate relativemovement between the earth's surface and the moving object.
 41. Thesystem as recited in claim 32 further comprising means for regulatingthe intensity of the IR light applied to the first template.
 42. Thesystem as recited in claim 32 further comprising means for regulatingthe diameter of the IR light applied to the first template.
 43. Thesystem as recited in claim 32 wherein movement of said first templateresults in relative movement between the first and second light signalson the detector elements.
 44. The system as recited in claim 1 whereinsaid second dynamically positionable infrared frequency light sourcecomprises:(a) a second source of infrared frequency light; (b) a secondscannable template formed to generate a second infrared frequency lightsignal upon application of the infrared light to the second template.45. The system as recited in claim 44 wherein the second template isconstructed to have at least one aperture formed therein, said aperturebeing designed to produce an image representative of a scene of theobject moving in relation to the earth's surface.
 46. The system asrecited in claim 44 wherein the second template is removable tofacilitate the use of templates having apertures designed to produceimages representative of different types of objects moving in relationto the earth's surface.
 47. The system as recited in claim 44 whereinthe second template is constructed to have a sapphire substrate.
 48. Thesystem as recited in claim 44 wherein the OSTG further comprises asecond optical filter disposed intermediate the second source of IRfrequency light and the second template, said second optical filterbeing operative to limit light frequencies within the IR light appliedto the second template.
 49. The system as recited in claim 44 whereinsaid positioning apparatus further comprises a second servo mechanismfor regulating the position of the second template.
 50. The system asrecited in claim 49 wherein said second servo mechanism is operative toregulate the location at which IR light is applied to the secondtemplate.
 51. The system as recited in claim 49 wherein said secondservo mechanism is operative to simulate relative movement between thedetector and the moving object.
 52. The system as recited in claim 49wherein said second servo mechanism is operative to simulate relativemovement between the earth's surface and the moving object.
 53. Thesystem as recited in claim 44 further comprising means for regulatingthe intensity of IR light applied to the second template.
 54. The systemas recited in claim 44 further comprising means for regulating thediameter of IR light applied to the second template.
 55. The system asrecited in claim 44 wherein movement of said second template results inrelative movement between the first and second light signal on thedetector elements.